const app = getApp()
class SignOnline {
    constructor(e){
        this.eventListener = e
    }
    ctx = ''
    canvasWidth =  0
    canvasHeight=  0
    transparent= 1 // 透明度
    selectColor= 'black'
    lineColor= '#000' // 颜色
    lineSize= 1.5  // 笔记倍数
    lineMin= 0.5   // 最小笔画半径
    lineMax= 4    // 最大笔画半径
    pressure= 1     // 默认压力
    smoothness= 60  //顺滑度，用60的距离来计算速度
    currentPoint= {}
    currentLine= []  // 当前线条
    firstTouch= true // 第一次触发
    radius= 1 //画圆的半径
    cutArea= { top: 0, right: 0, bottom: 0, left: 0 } //裁剪区域
    bethelPoint= []  //保存所有线条 生成的贝塞尔点；
    lastPoint= 0
    chirography= [] //笔迹
    currentChirography= {} //当前笔迹
    linePrack= [] //划线轨迹 , 生成线条的实际点


    // 初始化
    init(){
         wx.createSelectorQuery().select("#canvas").context((res)=> {
           console.log(res)
          this.ctx =  res.context
        })
        .exec();
        
        var query = wx.createSelectorQuery();
        query.select('.canvas').boundingClientRect(rect => {
            this.canvasWidth= rect.width,
            this.canvasHeight= rect.height
        }).exec();
      }
      //预览
      previewCanvasImg(){
        return new Promise((resolve,reject)=>{
          const _that = this
          wx.canvasToTempFilePath({
                 canvasId: 'handWriting',
                 fileType: 'png',
                 quality: 1, //图片质量
                 success(res) {
                      //图片生成base64
                      wx.getFileSystemManager().readFile({
                          filePath: res.tempFilePath, //选择图片返回的相对路径
                          encoding: 'base64', //编码格式
                          success: res => { //成功的回调
                            resolve(res.data)
                 }
     
             })
          }
        })
       
   
    })
   
   }
     // 笔迹结束
     uploadScaleEnd (e) {
       if (e.type != 'touchend') return 0;
       let point = {
         x: e.changedTouches[0].x,
         y: e.changedTouches[0].y
       }
         this.lastPoint=this.currentPoint,
         this.currentPoint= point
       let currentLine = this.currentLine
       currentLine.unshift({
         time: new Date().getTime(),
         dis: this.distance(this.currentPoint, this.lastPoint),
         x: point.x,
         y: point.y
       })
    
       if (currentLine.length > 2) {
         var info = (currentLine[0].time - currentLine[currentLine.length - 1].time) / currentLine.length;
       }
       //一笔结束，保存笔迹的坐标点，清空，当前笔迹
       //增加判断是否在手写区域；
       this.pointToLine(currentLine);
       var currentChirography = {
         lineSize: this.lineSize,
         lineColor: this.lineColor
       };
       var chirography = this.chirography
       chirography.unshift(currentChirography);
        this.chirography = chirography
       var linePrack = this.linePrack
       linePrack.unshift(this.currentLine);
        this.linePrack = linePrack
        this.currentLine = []
     }

   

     // 笔迹移动
     uploadScaleMove (e) {
       if (e.type != 'touchmove') return false;
       if (e.cancelable) {
         // 判断默认行为是否已经被禁用
         if (!e.defaultPrevented) {
           e.preventDefault();
         }
       }
       let point = {
         x: e.touches[0].x,
         y: e.touches[0].y
       }
   
       //测试裁剪
       if (point.y < this.cutArea.top) {
         this.cutArea.top = point.y;
       }
       if (point.y < 0) this.cutArea.top = 0;
   
       if (point.x > this.cutArea.right) {
         this.cutArea.right = point.x;
       }
       if (this.canvasWidth - point.x <= 0) {
         this.cutArea.right = this.canvasWidth;
       }
       if (point.y > this.cutArea.bottom) {
         this.cutArea.bottom = point.y;
       }
       if (this.canvasHeight - point.y <= 0) {
         this.cutArea.bottom = this.canvasHeight;
       }
       if (point.x < this.cutArea.left) {
         this.cutArea.left = point.x;
       }
       if (point.x < 0) this.cutArea.left = 0;
         this.lastPoint= this.currentPoint,
         this.currentPoint = point
       let currentLine = this.currentLine
       currentLine.unshift({
         time: new Date().getTime(),
         dis: this.distance(this.currentPoint, this.lastPoint),
         x: point.x,
         y: point.y
       })
       this.pointToLine(currentLine);
     }
      // 笔迹开始
      uploadScaleStart (e) {
       if (e.type != 'touchstart') return false;
       let ctx = this.ctx;
       console.log(ctx)
       ctx.setFillStyle(this.lineColor);  // 初始线条设置颜色
       let currentPoint = {
         x: e.touches[0].x,
         y: e.touches[0].y
       }
       let currentLine = this.currentLine;
       currentLine.unshift({
         time: new Date().getTime(),
         dis: 0,
         x: currentPoint.x,
         y: currentPoint.y
       })
         this.currentPoint = currentPoint
       if (this.firstTouch) {
           this.cutArea = { top: currentPoint.y, right: currentPoint.x, bottom: currentPoint.y, left: currentPoint.x },
           this.firstTouch = false
           this.eventListener()
       }
       this.pointToLine(currentLine);
     }
     retDraw () {
       this.ctx.clearRect(0, 0, 700, 730)
       this.ctx.draw()
       this.eventListener()
       this.firstTouch = true
     }
   
     //画两点之间的线条；参数为:line，会绘制最近的开始的两个点；
     pointToLine (line) {
       this.calcBethelLine(line);
       return;
     }
     //计算插值的方式；
     calcBethelLine (line) {
       if (line.length <= 1) {
         line[0].r = this.radius;
         return;
       }
       let x0, x1, x2, y0, y1, y2, r0, r1, r2, len, lastRadius, dis = 0, time = 0, curveValue = 0.5;
       if (line.length <= 2) {
         x0 = line[1].x
         y0 = line[1].y
         x2 = line[1].x + (line[0].x - line[1].x) * curveValue;
         y2 = line[1].y + (line[0].y - line[1].y) * curveValue;
         x1 = x0 + (x2 - x0) * curveValue;
         y1 = y0 + (y2 - y0) * curveValue;;
   
       } else {
         x0 = line[2].x + (line[1].x - line[2].x) * curveValue;
         y0 = line[2].y + (line[1].y - line[2].y) * curveValue;
         x1 = line[1].x;
         y1 = line[1].y;
         x2 = x1 + (line[0].x - x1) * curveValue;
         y2 = y1 + (line[0].y - y1) * curveValue;
       }
       //从计算公式看，三个点分别是(x0,y0),(x1,y1),(x2,y2) ；(x1,y1)这个是控制点，控制点不会落在曲线上；实际上，这个点还会手写获取的实际点，却落在曲线上
       len = this.distance({ x: x2, y: y2 }, { x: x0, y: y0 });
       lastRadius = this.radius;
       for (let n = 0; n < line.length - 1; n++) {
         dis += line[n].dis;
         time += line[n].time - line[n + 1].time;
         if (dis > this.smoothness) break;
       }
         this.radius= Math.min(time / len * this.pressure + this.lineMin, this.lineMax) * this.lineSize
       line[0].r = this.radius;
       //计算笔迹半径；
       if (line.length <= 2) {
         r0 = (lastRadius + this.radius) / 2;
         r1 = r0;
         r2 = r1;
         //return;
       } else {
         r0 = (line[2].r + line[1].r) / 2;
         r1 = line[1].r;
         r2 = (line[1].r + line[0].r) / 2;
       }
       let n = 5;
       let point = [];
       for (let i = 0; i < n; i++) {
         let t = i / (n - 1);
         let x = (1 - t) * (1 - t) * x0 + 2 * t * (1 - t) * x1 + t * t * x2;
         let y = (1 - t) * (1 - t) * y0 + 2 * t * (1 - t) * y1 + t * t * y2;
         let r = lastRadius + (this.radius - lastRadius) / n * i;
         point.push({ x: x, y: y, r: r });
         if (point.length === 3) {
           let a = this.ctaCalc(point[0].x, point[0].y, point[0].r, point[1].x, point[1].y, point[1].r, point[2].x, point[2].y, point[2].r);
           a[0].color = this.lineColor;
           this.bethelDraw(a, 1);
           point = [{ x: x, y: y, r: r }];
         }
       }
         this.currentLine =  line
     }
     //求两点之间距离
     distance (a, b) {
       let x = b.x - a.x;
       let y = b.y - a.y;
       return Math.sqrt(x * x + y * y);
     }
     ctaCalc (x0, y0, r0, x1, y1, r1, x2, y2, r2) {
       let a = [], vx01, vy01, norm, n_x0, n_y0, vx21, vy21, n_x2, n_y2;
       vx01 = x1 - x0;
       vy01 = y1 - y0;
       norm = Math.sqrt(vx01 * vx01 + vy01 * vy01 + 0.0001) * 2;
       vx01 = vx01 / norm * r0;
       vy01 = vy01 / norm * r0;
       n_x0 = vy01;
       n_y0 = -vx01;
       vx21 = x1 - x2;
       vy21 = y1 - y2;
       norm = Math.sqrt(vx21 * vx21 + vy21 * vy21 + 0.0001) * 2;
       vx21 = vx21 / norm * r2;
       vy21 = vy21 / norm * r2;
       n_x2 = -vy21;
       n_y2 = vx21;
       a.push({ mx: x0 + n_x0, my: y0 + n_y0, color: "#1A1A1A" });
       a.push({ c1x: x1 + n_x0, c1y: y1 + n_y0, c2x: x1 + n_x2, c2y: y1 + n_y2, ex: x2 + n_x2, ey: y2 + n_y2 });
       a.push({ c1x: x2 + n_x2 - vx21, c1y: y2 + n_y2 - vy21, c2x: x2 - n_x2 - vx21, c2y: y2 - n_y2 - vy21, ex: x2 - n_x2, ey: y2 - n_y2 });
       a.push({ c1x: x1 - n_x2, c1y: y1 - n_y2, c2x: x1 - n_x0, c2y: y1 - n_y0, ex: x0 - n_x0, ey: y0 - n_y0 });
       a.push({ c1x: x0 - n_x0 - vx01, c1y: y0 - n_y0 - vy01, c2x: x0 + n_x0 - vx01, c2y: y0 + n_y0 - vy01, ex: x0 + n_x0, ey: y0 + n_y0 });
       a[0].mx = a[0].mx.toFixed(1);
       a[0].mx = parseFloat(a[0].mx);
       a[0].my = a[0].my.toFixed(1);
       a[0].my = parseFloat(a[0].my);
       for (let i = 1; i < a.length; i++) {
         a[i].c1x = a[i].c1x.toFixed(1);
         a[i].c1x = parseFloat(a[i].c1x);
         a[i].c1y = a[i].c1y.toFixed(1);
         a[i].c1y = parseFloat(a[i].c1y);
         a[i].c2x = a[i].c2x.toFixed(1);
         a[i].c2x = parseFloat(a[i].c2x);
         a[i].c2y = a[i].c2y.toFixed(1);
         a[i].c2y = parseFloat(a[i].c2y);
         a[i].ex = a[i].ex.toFixed(1);
         a[i].ex = parseFloat(a[i].ex);
         a[i].ey = a[i].ey.toFixed(1);
         a[i].ey = parseFloat(a[i].ey);
       }
       return a;
     }
     bethelDraw (point, is_fill, color) {
       let ctx = this.ctx;
       ctx.beginPath();
       ctx.moveTo(point[0].mx, point[0].my);
       if (undefined != color) {
         ctx.setFillStyle(color);
         ctx.setStrokeStyle(color);
       } else {
         ctx.setFillStyle(point[0].color);
         ctx.setStrokeStyle(point[0].color);
       }
       for (let i = 1; i < point.length; i++) {
         ctx.bezierCurveTo(point[i].c1x, point[i].c1y, point[i].c2x, point[i].c2y, point[i].ex, point[i].ey);
       }
       ctx.stroke();
       if (undefined != is_fill) {
         ctx.fill(); //填充图形 ( 后绘制的图形会覆盖前面的图形, 绘制时注意先后顺序 )
       }
       ctx.draw(true)
     }
     selectColorEvent (event) {
       console.log(event)
       var color = event.currentTarget.dataset.colorValue;
       var colorSelected = event.currentTarget.dataset.color;
        this.selectColor = colorSelected,
        this.lineColor =  color
     }

}

export default SignOnline